As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CLIMB, THE LEFT MAIN LANDING GEAR DOOR OPEN LIGHT ILLUMINATED AFTER LANDING GEAR RETRACTION. FOLLOWED COCKPIT OPERATING MANUAL PROCEDURE AND LIGHT EXTINGUISHED AFTER LANDING GEAR WAS EXTENDED FOR LANDING. AIRCRAFT RETURNED TO DTW AND LANDED WITHOUT INCIDENT. ADJUSTED LEFT MAIN LANDING GEAR DOOR LATCH AND ROLLER ASSEMBLY, OPERATIONAL CHECK GOOD.